What does "preheating" achieve in the context of GTAW?

Preheating in the context of Gas Tungsten Arc Welding (GTAW) primarily serves the purpose of heating the base metals before the welding process begins. This practice is crucial because it helps to reduce thermal stress that can occur during welding, which might otherwise lead to warping, cracking, or other undesirable defects in the weld. By bringing the base metals to a more uniform temperature, preheating contributes to better fusion between the workpieces, thereby enhancing the overall quality of the weld.

Furthermore, preheating can improve the fluidity of the weld pool, allowing for better penetration and fusion with the base material. This can also help in managing the heat-affected zone more effectively, maintaining the integrity of the surrounding material. Overall, preheating is an essential technique in GTAW for achieving strong, quality welds, especially when working with thicker materials or metals that are more prone to thermal stresses.